In recent years, with the virtualization of open systems and servers, management of systems is becoming complicated. Consequently, using storage systems becomes common from the viewpoint of easily managing the systems or flexibly coping with a rapid increase in amount of data.
In the storage systems, disks with different speeds can be used. For example, examples of the disks include solid state disks (SSDs), serial attached small computer system interface hard disk drives (SAS HDDs), serial advanced technology attachment (SATA) HDDs, and the like.
In such a storage system, there may be a case in which several types of disks that have different speeds are used in the storage system and a storage area that is referred to as a single volume is created. Furthermore, for disks with different speeds in a single volume, a technology of tiering storage in an automated way, in which a storage location of data is determined according to a use frequency has been widely used.
If the technology of tiering storage in an automated way is used, for example, data that is frequently used is stored in a high speed disk in a volume, whereas data that is less frequently used is stored in a low speed disk in the volume. Then, due to automated storage tiering, it is possible to implement high-capacity high-speed storage devices at low cost.
Furthermore, for performance adjustment of storage, for example, adjustment of the band limit width of a data transfer path between a volume and a server that executes an application is performed. This function is sometimes referred to as the Quality of Service (QoS).
As a technology of adjusting the performance of storage, for example, there is a conventional technology of adjusting an amount of data passing through multipath channels. Furthermore, there is a conventional technology of determining each piece of data is allocated to which of disks with different speeds. Furthermore, there is a conventional technology of adjusting the performance by adjusting cache adjustment and prefetch target.
Patent Document 1: Japanese Laid-open Patent Publication No. 2008-108050
Patent Document 2: Japanese National Publication of International Patent Application No. 2013-527942
Patent Document 3: Japanese Laid-open Patent Publication No. 2003-150419
If the performance of a storage system is adjusted, it is conceivable to implement an appropriate performance by automatically calculating, using the distribution ratio of the current actual measurement and the performance ratio of each disk, a target performance and by adjusting the band limit width or distribution ratio of the disks. However, if a target performance is calculated by using the distribution ratio of the actual measurement, the difference between the calculated target performance and the distribution ratio of the actual measurement occurs due to approximately the influence of a difference of the performance ratio of the disks. Consequently, even if the performance is adjusted so as to satisfy the calculated target performance, insufficient adjustment is only performed on the band limit width and thus the distribution ratio of the disks is almost the same as that of the actual measurement.
Furthermore, with the conventional technology of adjusting an amount of data passing through a multipath path channels, the distribution ratio of disks is not considered; therefore, it is difficult to appropriately adjust the distribution ratio of the disks. Furthermore, even if the conventional technology that determines disks in each of which a storage area for each piece of data is allocated, it is also difficult to appropriately adjust the distribution ratio of the disks in the tired storage. Furthermore, even if the conventional technology that adjusts the cache adjustment and the prefetch target, it is also difficult to appropriately and automatically adjust the distribution ratio of disks in accordance with the performance ratio that is requested for each tier.